Since the advent of paper money, counterfeiting is a major concern. The ability of individuals or organizations to generate and pass counterfeit currency can have devastating effects on businesses and nations. Tools available to authorities charged with fighting counterfeiting have advanced such that counterfeiting by amateur and/or unorganized groups has been largely eliminated.
However, advances in technology, such as scanners, color laser printers and image processing through PCs, are beginning to tip the scales in favor of the counterfeiters again. This is especially true where the counterfeiters are large, organized groups. In extreme cases, such counterfeiting can lead to destabilized economies or dangerous situations. For example, extremist groups can use counterfeiting to procure weapons for terrorist activities. In another example, a country may try to destabilize the economy of an enemy by introducing large sums of counterfeit currency to its enemy's economy. Further, counterfeiting occurrences are becoming more difficult to detect. For example, today, counterfeit bills can be made to look and feel authentic. This is because they often use the same printing device, paper, ink, and other technology as used for printing legitimate currency. As a result, often, the only limitation on such organized counterfeiters is that they cannot invent new serial numbers. Consequently, they must use the same (duplicate) serial numbers as legitimate currency. Consequently, a manner for detecting occurrences of counterfeiting and the identity of the counterfeiters is required.